1. Field of the Invention
The present invention relates to techniques for determining a charging class of image data handled in a color printing apparatus and a color printing system.
2. Description of the Related Art
Japanese Patent Laid-Open No. 2012-32668 discloses a technique for generating a reduced image (hereinafter, referred to as a “thumbnail image”) from an image to be printed, and determining, based on whether each pixel of a generated thumbnail image is a color pixel or a black-and-white pixel, a charging amount required for printing the image to be printed. In the technique of Japanese Patent Laid-Open No. 2012-32668, the speed of charging class determination processing is increased by utilizing a thumbnail image.
For example, an image, such as a stamp image or a copy-forgery-inhibited pattern image, (hereinafter, referred to as an “additional image”) may be combined with an image to be printed, but the technique of the Japanese Patent Laid-Open No. 2012-32668 described above does not take into consideration such a case. That is, the method of Japanese Patent Laid-Open No. 2012-32668, in which color/monochrome determination is performed based only on a thumbnail image generated from an image to be printed, may result in an inappropriate charging amount. For example, in a case where after performing the charging determination, image processing that causes a ratio of the number of color pixels to greatly fluctuate is executed; an output result might not match a result of the charging determination.